Spatial anti-aliasing

In digital signal processing, spatial anti-aliasing is a technique for minimizing the distortion artifacts known as aliasing when representing a high-resolution image at a lower resolution. Anti-aliasing is used in digital photography, computer graphics, digital audio, and many other applications.1. As calculated with the program 'MandelZot'2. Anti-aliased by blurring and down-sampling by a factor of five3. Edge points interpolated, then anti-aliased and down-sampled4. An enhancement of the points removed from the previous image5. Down-sampled again, without anti-aliasing1) A picture of a particular spiral feature of the Mandelbrot set.2) 4 samples per pixel.3) 25 samples per pixel.4) 400 samples per pixel. In digital signal processing, spatial anti-aliasing is a technique for minimizing the distortion artifacts known as aliasing when representing a high-resolution image at a lower resolution. Anti-aliasing is used in digital photography, computer graphics, digital audio, and many other applications. Anti-aliasing means removing signal components that have a higher frequency than is able to be properly resolved by the recording (or sampling) device. This removal is done before (re)sampling at a lower resolution. When sampling is performed without removing this part of the signal, it causes undesirable artifacts such as the black-and-white noise near the top of figure 1-a below. In signal acquisition and audio, anti-aliasing is often done using an analogue anti-aliasing filter to remove the out-of-band component of the input signal prior to sampling with an analogue-to-digital converter. In digital photography, optical anti-aliasing filters made of birefringent materials smooth the signal in the spatial optical domain. The anti-aliasing filter essentially blurs the image slightly in order to reduce the resolution to or below that achievable by the digital sensor (the larger the pixel pitch, the lower the achievable resolution at the sensor level).